Problem: Which of these numbers is composite? ${17,\ 47,\ 53,\ 59,\ 69}$
Solution: A composite number is a number that has more than two factors (including 1 and itself). 17, 47, 53, and 59 each have only two factors. The factors of 69 are 1, 3, 23, and 69. Thus, 69 is the composite number.